In a communications system, channel encoding is usually performed to improve reliability of data transmission and ensure quality of communication. Currently, a 5G mobile communications system includes three major application scenarios: enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC), new requirements are put forward for data communication, and a polar (polar) code is a first channel encoding method that can be strictly proved to “have reached” a channel capacity, and may be applicable to a 5G communications system and a future communications system.